Electrical power tools are in widespread use, and with improving battery technology, cordless tools are becoming lighter, more efficient and more common. Any given user may have several such tools for performing different functions around the home, garden or job site. There have been many attempts at designing such tools to be modular, in order to avoid unnecessary duplication of hardware common to all of a user's power tools.
The design of the interface between common and specific modules is critical to the safety and reliability of such a modular system. When transferring electrical power or signals across such an interface, care should be taken to ensure reliable electrical contact. In addition, the modules should lock together in a manner which avoids inadvertent separation.
Modular cordless systems, in which a common module contains a storage battery and task-specific modules contain electric motors, require electrical power to be transferred across the module interface. It is important in many applications that motors of such tools not be inadvertently energized during assembly and disassembly of the common module, or battery pack, with any given task-specific module, or tool chassis.